2026 EJC JC2 H2 Biology Prelims P3 (Q)

©EJC 2026 9477/03/J2H2PRELIM/2026 [Turn over EUNOIA JUNIOR COLLEGE JC2 Preliminary Examinations 2026 General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME CIVICS GROUP 2 5 - REGISTRATION NUMBER H2 Biology Paper 3 Long Structured and Free-Response Questions 9477/03 16 September 2026 2 hours Additional Materials: 4-page Answer Booklet READ THESE INSTRUCTIONS FIRST Write your name, civics group and registration number on all the work you hand in. Write your answers in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use paper clips, highlighters, glue, or correction fluid/tape. Section A Answer all questions on the Question Paper. Section B Answer one question on the 4-page Answer Booklet provided. Write your answer to each part of the question on a fresh sheet of paper. The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in brackets [ ] at the end of each question or part question. At the end of the examination, ensure that you submit both the Question Paper and Answer Booklet. This document consists of 14 printed pages and 2 blank pages. For Examiner’s Use Section A 1 2 3 Section B 4 OR 5 Total 75

2 ©EJC 2026 9477/03/J2H2PRELIM/2026 BLANK PAGE

3 ©EJC 2026 9477/03/J2H2PRELIM/2026 [Turn over Section A Answer all questions on the Question Paper. 1 A species of leaf -eating beetle, Coleoptera eunoia, feeds on a specific plant that produces a highly hydrophobic, non-polar toxic metabolite. A resistant population of C. eunoia produces a water-soluble, globular enzyme called Eunoiase in their gut, which effectively binds to and degrades this toxin. Eunoiase is coded for by the eun gene. There are no disulfide bonds in Eunoiase. (a) Describe how the structure of the Eunoiase enzyme is maintained in the aqueous environment of the beetle's gut. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ………………………………………………………………………………………………………… [3] (b) (i) The eun gene is expressed at high levels in the gut, but not in the beetle's eyes. It is thought that DNA methylation might have occurred in the eye cells. Explain how DNA methylation prevents the expression of the eun gene in the eyes. ………………………………………………………………………………………………...…… ……….…………………………………………………………………………………………..... ..………………….………………………………………………………………………………… ………………………….……………………………………………………………………..…… ………………………………….…………………………………………….....………………… …………………………………………….……………………………………..…………….. [3]

4 ©EJC 2026 9477/03/J2H2PRELIM/2026 (ii) Multiple variants of the Eunoiase enzyme were found in various parts of the beetle’s body. Researchers found that their polypeptide lengths were different, despite being coded by the same eun gene. Explain the mechanism that resulted in the multiple variants of Eunoiase enzyme. ………………………………………………………………………………………………...…… ……….…………………………………………………………………………………………..... ..………………….………………………………………………………………………………… ………………………….……………………………………………………………………..…… ………………………………….…………………………………………….....………………… …………………………………………….……………………………………..…………….. [3]

5 ©EJC 2026 9477/03/J2H2PRELIM/2026 [Turn over (c) A susceptible population of beetles possesses a mutant allele (eun-m). This allele arose from a deletion of 100 base pairs within the coding sequence of the eun gene. Fig. 1.1 shows the toxin degradation activity of the wild -type (normal) Eunoiase and mutant Eunoiase over time. Explain the difference in toxin degradation activity of the two enzymes as shown in Fig. 1.1. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ………………………………………………………………………………………………………… [4] Wild-type Eunoiase Mutant Eunoiase Fig. 1.1 Time / min Wild-type (normal) Mutant Mass of toxin degraded / µg

6 ©EJC 2026 9477/03/J2H2PRELIM/2026 (d) Researchers isolated genomic DNA from a wild-type beetle and a homozygous mutant beetle. They used Polymerase Chain Reaction (PCR) to amplify the eun gene before separating the DNA fragments via agarose gel electrophoresis. (i) Fig. 1.2 shows the gel slab under UV light after gel electrophoresis. A molecular ladder was added to the well in Lane 1. Lanes 2 and 3 contained the PCR products from the wild-type allele and Lane 4 contained the PCR product from the mutant allele (eun-m). Draw on Fig 1.2 to indicate the band for the PCR product of the eun-m allele. [1] (ii) Explain the position of the band you have drawn in (i). ………………………………….…………………………………………….....………………… …………………………………………….……………………………………..…………….. [1] Lane 1 Lane 2 Lane 3 Lane 4 4kb 3kb 2kb 3.5kb 2.5kb Fig. 1.2

7 ©EJC 2026 9477/03/J2H2PRELIM/2026 [Turn over (e) Colour in the beetles are determined by two genes on different autosomes. A pure-breeding brown beetle mated with a pure-breeding albino (white) beetle. The F1 offspring were all brown in colour. When two F1 offspring were mated, the resultant F2 offspring were found to be in the following numbers: 198 brown, 66 tan and 88 albino. Using the symbols B and b to represent type of colour pigment, as well as E and e to represent pigment deposition, draw a genetic diagram to show the cross between the F1 beetles and the resulting F2 phenotypic ratio. [4]

8 ©EJC 2026 9477/03/J2H2PRELIM/2026 (f) The plant toxin is also lethal to certain soil bacteria, though some bacteria possess a eun resistance gene on a plasmid. Compare the structure of the bacterial genome with the eukaryotic genome of the C. eunoia beetle. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ………………………………………………………………………………………………………… [3] (g) Researchers discovered that Coleoptera eunoia is part of a much larger evolutionary lineage. An ancestral population of these beetles from the mainland was likely blown out to sea and successfully colonised a group of newly formed volcanic islands a few million years ago. Today, researchers have identified the mainland species, Coleoptera eunoia, alongside five distinct, closely related species (Coleoptera akila icus, Coleoptera edericus , Coleoptera isamicus, Coleoptera oraicus, and Coleoptera uzuricus). To determine their evolutionary relationships, researchers sequenced the eun gene from all six species and used the nucleotide data to construct the phylogenetic tree below in Fig. 1.3. Recent Past Fig. 1.3

9 ©EJC 2026 9477/03/J2H2PRELIM/2026 [Turn over (i) A student stated that “C. edericus is more closely related to C. eunoia than C. isamicus, C. oraicus or C. uzuricus.” Using Fig. 1.3, evaluate the accuracy of the student’s statement and explain your answer. ..………………….………………………………………………………………………………… ………………………….……………………………………………………………………..…… ………………………………….…………………………………………….....………………… …………………………………………….……………………………………..…………….. [2] (ii) Each volcanic island is occupied by a distinct beetle species. Explain the evolutionary me